Ta có:
\(\left\{{}\begin{matrix}n_{CuO}=\frac{40}{80}=0,5\left(mol\right)\\n_{H2}=\frac{6,72}{22,4}=0,3\left(mol\right)\end{matrix}\right.\)
\(PTHH:CuO+H_2\rightarrow Cu+H_2O\)
Lập tỉ lệ nCuO > nH2 nên CuO dư
\(n_{CuO\left(pư\right)}=n_{Cu}=n_{H2O}=n_{H2}=0,3\left(mol\right)\)
\(\Rightarrow n_{CuO\left(du\right)}=0,5-0,3=0,2\left(mol\right)\)
\(\Rightarrow\left\{{}\begin{matrix}a=0,3.18=5,4\left(g\right)\\b=0,2.80+0,3.64=35,2\left(g\right)\end{matrix}\right.\)